With a rapid increase of the computer power consumption, a reduction in energy cost has recently been desired.
For example, suppose that a computer is constituted by connecting a plurality of CPU sockets each including one or more CPU (Central Processing Unit) cores, a memory controller, a memory, and a crossbar switch. There is a known technology in which the OS (Operating System) brings unneeded CPU cores into a power saving state when the amount of processing needed is low, and brings an entire CPU socket into the power saving state when all the CPU cores in the CPU socket are in the power saving state and there is no access from the memory controller in the CPU socket to the memory connected.
PTL 1 proposes a method for a system that performs automatic data migration between a plurality of memory storage devices containing application program data. The method includes monitoring data accesses, determining to change the memory allocations of the data in consideration of service-level requirements of the application program, and automatically transferring data between the plurality of memory storage devices according to the determination.
PTL 2 proposes a method for a system that includes a plurality of modules with a built-in data memory. In the method, memory capacities and power consumption are stored in a backup management table. Upon transition to backup, the table is consulted to determine whether or not the data stored in each module can be collected to some of the modules for lower power consumption. If the data can be collected, all the data is transferred from the rest of the modules to the certain module(s), and the power supply to the rest of the modules is stopped to reduce power during data backup.